/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
 *
 */


package javax.management.openmbean;

// java import
//

import java.io.InvalidObjectException;
import java.io.ObjectStreamException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Date;
import java.util.Map;
import java.util.HashMap;

// jmx import
//
import javax.management.ObjectName;


/**
 * The <code>SimpleType</code> class is the <i>open type</i> class whose instances describe all
 * <i>open data</i> values which are neither arrays, nor {@link CompositeData CompositeData} values,
 * nor {@link TabularData TabularData} values. It predefines all its possible instances as static
 * fields, and has no public constructor. <p> Given a <code>SimpleType</code> instance describing
 * values whose Java class name is <i>className</i>, the internal fields corresponding to the name
 * and description of this <code>SimpleType</code> instance are also set to <i>className</i>. In
 * other words, its methods <code>getClassName</code>, <code>getTypeName</code> and
 * <code>getDescription</code> all return the same string value <i>className</i>.
 *
 * @since 1.5
 */
public final class SimpleType<T> extends OpenType<T> {

  /* Serial version */
  static final long serialVersionUID = 2215577471957694503L;

  // SimpleType instances.
  // IF YOU ADD A SimpleType, YOU MUST UPDATE OpenType and typeArray

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Void</code>.
   */
  public static final SimpleType<Void> VOID =
      new SimpleType<Void>(Void.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Boolean</code>.
   */
  public static final SimpleType<Boolean> BOOLEAN =
      new SimpleType<Boolean>(Boolean.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Character</code>.
   */
  public static final SimpleType<Character> CHARACTER =
      new SimpleType<Character>(Character.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Byte</code>.
   */
  public static final SimpleType<Byte> BYTE =
      new SimpleType<Byte>(Byte.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Short</code>.
   */
  public static final SimpleType<Short> SHORT =
      new SimpleType<Short>(Short.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Integer</code>.
   */
  public static final SimpleType<Integer> INTEGER =
      new SimpleType<Integer>(Integer.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Long</code>.
   */
  public static final SimpleType<Long> LONG =
      new SimpleType<Long>(Long.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Float</code>.
   */
  public static final SimpleType<Float> FLOAT =
      new SimpleType<Float>(Float.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.Double</code>.
   */
  public static final SimpleType<Double> DOUBLE =
      new SimpleType<Double>(Double.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.lang.String</code>.
   */
  public static final SimpleType<String> STRING =
      new SimpleType<String>(String.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.math.BigDecimal</code>.
   */
  public static final SimpleType<BigDecimal> BIGDECIMAL =
      new SimpleType<BigDecimal>(BigDecimal.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.math.BigInteger</code>.
   */
  public static final SimpleType<BigInteger> BIGINTEGER =
      new SimpleType<BigInteger>(BigInteger.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>java.util.Date</code>.
   */
  public static final SimpleType<Date> DATE =
      new SimpleType<Date>(Date.class);

  /**
   * The <code>SimpleType</code> instance describing values whose
   * Java class name is <code>javax.management.ObjectName</code>.
   */
  public static final SimpleType<ObjectName> OBJECTNAME =
      new SimpleType<ObjectName>(ObjectName.class);

  private static final SimpleType<?>[] typeArray = {
      VOID, BOOLEAN, CHARACTER, BYTE, SHORT, INTEGER, LONG, FLOAT,
      DOUBLE, STRING, BIGDECIMAL, BIGINTEGER, DATE, OBJECTNAME,
  };


  private transient Integer myHashCode = null;        // As this instance is immutable, these two values
  private transient String myToString = null;        // need only be calculated once.


    /* *** Constructor *** */

  private SimpleType(Class<T> valueClass) {
    super(valueClass.getName(), valueClass.getName(), valueClass.getName(),
        false);
  }


    /* *** SimpleType specific information methods *** */

  /**
   * Tests whether <var>obj</var> is a value for this
   * <code>SimpleType</code> instance.  <p> This method returns
   * <code>true</code> if and only if <var>obj</var> is not null and
   * <var>obj</var>'s class name is the same as the className field
   * defined for this <code>SimpleType</code> instance (ie the class
   * name returned by the {@link OpenType#getClassName()
   * getClassName} method).
   *
   * @param obj the object to be tested.
   * @return <code>true</code> if <var>obj</var> is a value for this <code>SimpleType</code>
   * instance.
   */
  public boolean isValue(Object obj) {

    // if obj is null, return false
    //
    if (obj == null) {
      return false;
    }

    // Test if obj's class name is the same as for this instance
    //
    return this.getClassName().equals(obj.getClass().getName());
  }


    /* *** Methods overriden from class Object *** */

  /**
   * Compares the specified <code>obj</code> parameter with this <code>SimpleType</code> instance
   * for equality. <p> Two <code>SimpleType</code> instances are equal if and only if their {@link
   * OpenType#getClassName() getClassName} methods return the same value.
   *
   * @param obj the object to be compared for equality with this <code>SimpleType</code> instance;
   * if <var>obj</var> is <code>null</code> or is not an instance of the class
   * <code>SimpleType</code>, <code>equals</code> returns <code>false</code>.
   * @return <code>true</code> if the specified object is equal to this <code>SimpleType</code>
   * instance.
   */
  public boolean equals(Object obj) {

        /* If it weren't for readReplace(), we could replace this method
           with just:
           return (this == obj);
        */

    if (!(obj instanceof SimpleType<?>)) {
      return false;
    }

    SimpleType<?> other = (SimpleType<?>) obj;

    // Test if other's className field is the same as for this instance
    //
    return this.getClassName().equals(other.getClassName());
  }

  /**
   * Returns the hash code value for this <code>SimpleType</code> instance. The hash code of a
   * <code>SimpleType</code> instance is the the hash code of the string value returned by the
   * {@link OpenType#getClassName() getClassName} method. <p> As <code>SimpleType</code> instances
   * are immutable, the hash code for this instance is calculated once, on the first call to
   * <code>hashCode</code>, and then the same value is returned for subsequent calls.
   *
   * @return the hash code value for this <code>SimpleType</code> instance
   */
  public int hashCode() {

    // Calculate the hash code value if it has not yet been done (ie 1st call to hashCode())
    //
    if (myHashCode == null) {
      myHashCode = Integer.valueOf(this.getClassName().hashCode());
    }

    // return always the same hash code for this instance (immutable)
    //
    return myHashCode.intValue();
  }

  /**
   * Returns a string representation of this <code>SimpleType</code> instance. <p> The string
   * representation consists of the name of this class (ie <code>javax.management.openmbean.SimpleType</code>)
   * and the type name for this instance (which is the java class name of the values this
   * <code>SimpleType</code> instance represents). <p> As <code>SimpleType</code> instances are
   * immutable, the string representation for this instance is calculated once, on the first call to
   * <code>toString</code>, and then the same value is returned for subsequent calls.
   *
   * @return a string representation of this <code>SimpleType</code> instance
   */
  public String toString() {

    // Calculate the string representation if it has not yet been done (ie 1st call to toString())
    //
    if (myToString == null) {
      myToString = this.getClass().getName() + "(name=" + getTypeName() + ")";
    }

    // return always the same string representation for this instance (immutable)
    //
    return myToString;
  }

  private static final Map<SimpleType<?>, SimpleType<?>> canonicalTypes =
      new HashMap<SimpleType<?>, SimpleType<?>>();

  static {
    for (int i = 0; i < typeArray.length; i++) {
      final SimpleType<?> type = typeArray[i];
      canonicalTypes.put(type, type);
    }
  }

  /**
   * Replace an object read from an {@link
   * java.io.ObjectInputStream} with the unique instance for that
   * value.
   *
   * @return the replacement object.
   * @throws ObjectStreamException if the read object cannot be resolved.
   */
  public Object readResolve() throws ObjectStreamException {
    final SimpleType<?> canonical = canonicalTypes.get(this);
    if (canonical == null) {
      // Should not happen
      throw new InvalidObjectException("Invalid SimpleType: " + this);
    }
    return canonical;
  }
}
